This invention relates to an explosive actuated hand tool for forming clean holes in sheet metal, with particular reference to electrical junction boxes and the like. Such boxes may be manufactured with one or more standard openings, as for a main cable, but frequently need to be further perforated to accommodate varying numbers of additional cables or wires as required by the electrical system being installed.
The formation of holes in junction boxes has heretofore been effected by means of a "chassis punch" which usually consists of a punch having two sharp pointed sections which nest in a die. To start punching a hole, a starter hole is drilled, the die and punch are positioned on opposite sides of the sheet metal and a bolt is inserted through the die and sheet metal hole and secured into the punch. Turning the bolt with a wrench draws the punch and die together and forces the sharp edges of the punch to cut the sheet metal. This operation takes considerable effort when done by hand. A pneumatic wrench, if available, makes it much easier.